In 1991, Cliff Deibel, owner of Deibel Lawn Service in Greeley, Colorado, got tired of using a 10 horsepower, air-cooled, single-cylinder lawnmower to service his customers. What Deibel really wanted was a lawnmower with more power and a longer life span. So he switched to a lawnmower with a liquid-cooled, diesel engine.

?There weren?t too many mowers with liquid-cooled engines around at that time, but I decided to try one out,? Deibel recalled. ?The machine had no bugs. It was big and powerful and ran like a charm.?

Over the next three years, Deibel bought three more diesel, liquid-cooled mowers. A decade later, he is still using the 1992 model, which he estimates has accrued more than 5,600 hours of use. In buying the liquid-cooled, diesel-fueled engine, Deibel was way ahead of the technology curve. While the liquid-cooled lawnmower had been around for some time before Deibel bought his model, it?s only been in the last few years that the engine has begun to make a significant impact on the landscape maintenance industry.

The Grasshopper Company, a Moundridge, Kansas-based mower manufacturer, has sold liquid-cooled models since 1984. Today, Grasshopper uses five different liquid-cooled engine sizes (two diesel and three gas) to power eleven different models in its product line. ?The liquid-cooled engine models are among our strongest sellers,? said Ruthanne Stucky, Grasshopper Company?s director of marketing.

Yet, despite the strong appearance of liquid-cooled mowers, not every contractor and manufacturer is sold on the idea that they?re the future of the lawn maintenance business. Dale Micetic, president of Terrain Systems in Phoenix, Arizona, said that other contractors might see practical value in the liquid cooled, but his company won?t be one of them. ?A contractor would have to be in tractor mode to use a liquid-cooled engine, and we don?t need an engine that size,? he explained. ?We operate in a desert where there is much more restrictive use of turf than in other parts of the country, so we don?t have large areas to maintain.?

American Honda Motor Company?s Power Equipment Division in Alpha-retta, Georgia, sells a 21-inch air-cooled lawnmower to the commercial market. Honda company executives believe that their small, walk-behind model doesn?t need the power of the liquid-cooled engine. ?We?ve found that our customers want a durable long-lasting lawnmower, but they also want it to be easy to use and simple in design,? explained Dennis Blanton, product development manager at American Honda Motor Company.

But sales of the liquid-cooled engine are increasing, and it does offer contractors a viable alternative to the air cooled. Professionals in the maintenance end of the business may be asking themselves: which engine type should I go with? The answer ? each engine type has its advantages, and it really depends on the needs of the company and its specific landscaping applications.

When asked, ?Why liquid-cooled engines?? one manufacturer explained that the new mowers, especially the larger size zero-turn radius types, are being built so well that they are outlasting the air-cooled engine. Liquid-cooled en-gines will help maximize the life of the entire machine. ?Many lawn care companies are using liquid-cooled models because they be-lieve it makes them more productive,? said John Chiera, national account manager for Briggs and Stratton, based in Milwaukee, Wisconsin. ?In their mind, horsepower equals speed, even though that may not always be true.?

About 13 percent of the lawnmowers they sold last year had liquid-cooled engines. ?Many contractors believe that a liquid-cooled engine is cleaner, quieter and more fuel efficient than the air-cooled model,? said Bob Walker, president of Walker Manufacturing.

Let?s look at the cost factor. No question about it, an air-cooled engine is cheaper. That?s because all the parts are contained in one unit, and unlike a liquid cooled, there are no radiators, hoses and other accessories. ?The difference in cost between air cooled and liquid cooled is only a couple of hundred dollars, but by the time you add and fit all the other accessories on the mower, the cost could add up to several hundred dollars,? Walker explained.

But simply looking at the initial cost may not be the best move in the long run. ?The liquid-cooled units will normally run longer, which means a contractor should get more mileage out of his machine, saving money in the long run,? Litt said. Chiera added, ?A liquid-cooled model will cost about 30 to 40 percent more to buy, but by the nature of its design, it will have 30 to 40 percent greater engine life, and 30 percent more fuel efficiency.?

Briggs and Stratton is a major engine manufacturer. The company has been providing 3-cylinder liquid-cooled engines since 1994. Earlier this year, they introduced a new 2-cylinder, liquid-cooled engine to lawnmower manufacturers.

Last fall, Kohler Engines in Kohler, Wisconsin, began producing two liquid-cooled models, rated at 22 and 25-hp, two years after launching its first model. ??We introduced the liquid-cooled model to give our customers more choices,? said Cameron Litt, product manager for Kohler Engines. ?We are now expanding the line because Kohler believes a growing number of contractors want to buy a mower with an engine that has more durability and horsepower.

So, what the choice may come down to is personal preference. ?Some contractors may want to keep their mowers as long as possible, but others may want to get rid of them before they acquire too much mileage,? Walker noted.

Besides running longer, a liquid cooled may also have better maintenance performance. After all, the air cooled does run hotter, and this makes the oil break down faster. ?I know from my experience that it costs less to maintain my liquid-cooled mowers because the maintenance level is longer,? Deibel said. To absorb the heat during operation, the liquid cooled circulates a liquid mixture, typically water and alcohol, and this helps prolong the life of an engine.

As Stucky explained, ?An air cooled should be easier to maintain, but it?s essential that it be kept clean to allow cooling by the surrounding air.? All you really need is compressed air to blow out the grass, dirt and other particles that collect in an air-cooled engine.

Simple enough, but a liquid-cooled engine does require much more attention to maintenance. A liquid-cooled engine is contained in a complete envelope. A nice feature, no doubt, but contractors will need to be concerned about the radiator, hoses and other accessories that come with the liquid cooled. It?s necessary, therefore, that a contractor spend time monitoring his employees to ensure that they handle the equipment properly, said Ricky Lockhart, operations manager for Landscape.com LLC in California. ?Employees will need to be educated about the importance of not puncturing a radiator and keeping the hoses connected,? he explained.

The environmental impact may be another important consideration. We?ve pointed out that the liquid-cooled engine is much more fuel efficient. It has a big environmental advantage as well. Liquid cooled are less noisy, which could be important to the contractor who works on a golf course or in a community where noise levels may be a concern. Offsetting that advantage, however, is the fact that liquid cooled is made of a coolant mixture, which could create a potential environmental hazard. ?You?ll have to be careful about replacing the mixture periodically and disposing of it safely,? Lockhart advised.

So both engines have their pluses and minuses, but choosing the right engine type may not be an either-or proposition. It?s true that the air cooled is a much smaller machine and is a practical choice for maintaining areas where the larger liquid-cooled units cannot tread. And because of their compact size, they are usually used to power entry-level commercial mowers, as well as smaller pieces of lawn care equipment, such as leaf blowers and log splitters.

If only the maintenance business was that simple. The fact is, no lawn or terrain is alike. So contractors like Deibel and Lockhart actually keep both types of machines on hand for the different terrain that their crews might have to work on.

As we can see, touting one type of machine as superior to the other is a futile and even foolish exercise. No two contractors will have the same needs, nor will they necessarily have to work on the same kind of turf. To make the right choice, a contractor needs to do his research and take a close look at his company?s needs. That?s the smart way to determine what engine type will give his company the best performance for the best value.